end2end? (was: RE: Where NAT disenfranchises the end-user ...

Mon Sep 10 21:34:46 UTC 2001

Firstly, please note the flamewar about NAT breaking or not breaking
PMTU discovery is a different flamewar from the RFC1918 numbered
links breaking PMTU discovery flamewar. And I am commenting here
on neither. The answers to both are clear if you read the
relevant docs.

However:

> That is what I truly love about NAT.
> It breaks totally inane filth like path mtu discovery.

Allegation of dubious merit aside:

Please suggest alternate legacy compatible mechanisms to
discover path MTU, or explain why you think fragmenting
stuff as a matter of course aides performance,
before you dismiss PMTU discovery as inane filth.

> I'm sure if someone had an MTU < ethernet on an
> internal router they wouldn't need NAT breaking path MTU discovery to
> bring it to their attention.

Like, say, ethernet LAN -> dialup routed connection -> Internet.
Or, urm, anything tunnelled between ethernet LANs passing at
some point over ethernet. Both, of course, extremely
uncommon applications.

So now tell me why being unable to do path MTU discovery
(somehow) is a good thing?

--
Alex Bligh
Personal Capacity